Taking Care of Moon Jellyfish


Our main goal is to help you learn about keeping jellyfish. Whether you’re a first-time aquarium owner or a seasoned saltwater hobbyist, there’s a small learning curve when it comes to jellyfish. We are here to make sure your experience with jellyfish and a jellyfish aquarium is fun and most importantly, successful.

Jellyfish are different than regular fish, in more ways than one

  • Fish can often be used to cycle a new aquarium. Jellyfish cannot as they are extremely sensitive to ammonia and nitrite, the toxic by-products of the Nitrogen Cycle.

  • When acclimating, jellyfish don’t require the “drip method” that’s commonly used for fish. Jellyfish must be acclimated in parts, where water is exchanged periodically between the shipping bag and your aquarium. Using the drip method would introduce bubbles to the jellyfish and can be extremely harmful.

  • Fish can tolerate being taken out of the water for a short period of time, such as moving them between containers. Jellyfish… not so much! Jellyfish should never be taken out of the water and should always been completely submerged when moving. Exposing jellyfish to the air allows air pockets to get stuck in the cavities of their body and if it goes unnoticed, it can severely damage their bodies.

Tips for keeping jellyfish happy

  • When your hands are clean, your water is clean! It’s good practice to always wash and dry your hands thoroughly before interacting with your aquarium. Any perfumes, lotions, or other foreign substances can contaminate the water and if it’s too much for the carbon to absorb, it can cause bodily damage to your jellies. For washing your hands, we recommend using hand soap that isn’t “anti-bacterial,” at least only for your jellyfish aquarium. If there’s any soap residue left on your hands, there’s a risk of it harming the beneficial bacteria in your filters.

  • Clean tools make a positive difference! It’s best to have tools specifically for your jellyfish aquarium - such as a turkey baster, bowl, cup, ladle, etc. These should be used for your jellies and only for your jellies. After every time you use them, give them a good rinse under tap water and let them air dry. This helps prevent dried salt from building up and cleans them of food residue.

  • Check your sump level! Evaporation is a common side effect of keeping a tank full of water and can drastically change your salinity if goes unnoticed for too long. If too much evaporation occurs, the salinity will increase because since only water evaporates out, it leaves a higher concentration of salt behind. In addition, if the sump water level gets too low and exposes the pump to air, it can cause it to suck in more air than water which introduces air bubbles to your system (bad for the jellies!) and creates mechanical issues within the pump (bad for the pump!). Checking in on your sump level once or twice a week can help keep track of where it is and how much water needs to be added to bring it back up. If you notice your sump low, test the salinity to determine whether to add saltwater (if the salinity is optimal) or freshwater (if the salinity is high and needs to come back down into optimal range).

  • Little Red Riding Hood Syndrome… but, for jellies! Feeding too much or too little can lead to growth issues with your jellies. If you feed too much, the jellies can become overstimulated and can’t keep the same pace of energy. If fed too little, they are not receiving enough nutrition and can grow thin or even shrink. Both can lead to thin, weak, inverted jellies - a.k.a. unhappy jellies! When feeding the first few times,